Building block



FIG. 1 is a front perspective view of the building block showing the present design.

FIG. 2 is a front view thereof.

FIG. 3 is a rear view thereof.

FIG. 4 is a right side view thereof.

FIG. 5 is a left side view thereof.

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The portions of the design shown in broken lines being for the purpose of illustrating environment only and form no part of the claimed design. 

CLAIM The ornamental design for a building block, as shown and described. 